Left Main Coronary Ostial Stenosis after Aortic Valve Replacement: A Case Report

 

 

Article By:

M. Sharma

D. Mascarenhas

 

Abstract

Coronary ostial stenosis is a rare but a potentially life-threatening complication of aortic valve replacement (AVR). It can present as acute coronary syndrome, left ventricular failure, ventricular arrhythmias or sudden death. Exact pathogenetic mechanism is not known but few hypotheses have been proposed. We present a case of left main coronary stenosis, 11 months after AVR done for symptomatic critical Aortic stenosis. A high index of clinical suspicion and a timely coronary angiography helped to determine the exact etiology. A percutaneous coronary intervention was done emergently. Patient has done very well so far.

 

Introduction :

Surgical aortic valve replacement (AVR) remains the cornerstone of treatment for symptomatic critical Aortic Stenosis (AS). It is rewarding for most of the patients but it can have several associated complications. Coronary ostial stenosis is a rare but potentially serious complication of AVR. It was first described by Roberts and Morrow in 1967.[1] It is estimated to occur in about 1 to 5% of all AVR procedures.[2-6] The exact cause of coronary ostial stenosis is still undetermined but few hypotheses have been proposed.[5] Symptoms are severe and generally appear  within  1  to  6  months   postoperatively. Coronary artery bypass grafting (CABG) is the typical treatment but percutaneous coronary intervention (PCI) has also yielded favorable outcomes.[7-12] We present a case of left main coronary ostial stenosis 11 months after AVR was done for symptomatic critical AS which was successfully managed with primary stent placement.

 

Case report :

In June 2015, a 67-year-old female with a long-standing  history  of  asymptomatic  critical  AS was referred for AVR after new onset of shortness of breath. A preoperative transesophageal echocardiogram showed aortic valve area of 0.6 cm2 with 2+ mitral regurgitation. Cardiac catheterization revealed no significant coronary artery disease and well-preserved left ventricular ejection fraction. She underwent insertion of a 19 mm St. Jude Biocor bioprosthetic aortic valve. Postoperatively patient did well. She was started on warfarin and discharged home. In May 2016, patient experienced shortness of breath with moderate exertion, which was new. She underwent a nuclear stress test (Cardiolite), which was abnormal (Figures 1, 2 and 3).

TC- Oct 2016 - 012 - Electrocardiograph during rest phase of the stress test TC- Oct 2016 - 013 - 3 mm ST depression in Lead II in recovery phase of stress test TC- Oct 2016 - 014 - Apical ischemia with left ventricular cavity dilatation (arrow) on nuclear (Cardiolite) imaging

 

Repeat coronary angiography revealed 99% narrowing of the left main coronary artery (LMCA) (Figure 4).

TC- Oct 2016 - 015 - Ostial stenosis of left main coronary artery (LMCA) (shown by arrow)

The left anterior descending artery, left circumflex and right coronary artery (RCA) did not reveal any discrete stenosis. After consultation with the cardiac surgeon and the family, the patient underwent urgent primary stent deployment of LMCA (Figure 5).

TC- Oct 2016 - 016 - LMCA post-stent placement (arrow)

A successful placement of an intra-aortic balloon pump was also done in the left femoral artery since this was a high-risk procedure. Patient recovered very well and was recommended 12 months of anti-platelet therapy.

 

Discussion:

Coronary ostial stenosis after AVR occurs most commonly in the LMCA but the RCA can also be affected.[3-5] Exact pathophysiologic mechanism of coronary ostial stenosis has not been determined. Various theories have been proposed. Roberts and Morrow[1] discovered AVR fibrous thickening in the aortic root and proximal coronary artery in autopsy subjects. No evidence of atherosclerosis was seen on histological examination.[5] Intimal thickening and fibrosis near the aortic root have been proposed[1] to be due to turbulent flow around the prosthetic valve leading to obstruction of the coronary ostia. There may be micro-injury and local hyperplastic reaction due to cardioplegic fluid and over-dilation of the vessel by the tip of the catheter during AVR and Tukiji et al have suggested an immunologic reaction to the bioprosthesis.[13, 14]

Coronary ostial stenosis after AVR generally presents as unstable angina, left ventricular heart failure, ventricular arrhythmias or sudden death.[7] High clinical suspicion is crucial. Prompt coronary angiography and emergent reperfusion strategies are vital for management. CABG may not always be a safe option, mainly due to the proximity of the graft site to the area of prior operation.[7] High incidence of perioperative infarction, increased mortality and poor long-term outcome[2,3] has been reported with CABG. Several reports have shown good early and late outcomes with PCI and stent implantation.[5,6,13,14]

 

Conclusion:

Though rare, coronary ostial stenosis after AVR should be suspected in patients presenting with new relevant symptoms. Mostly, such cases have been reported to occur within 1 to 6 months after AVR, but it can manifest even later, as evident by our case. Thorough history and physical examination and timely coronary angiography should be performed if the suspicion of coronary ostial stenosis is high. It can be fatal due to potential complications of acute coronary syndrome, left ventricular heart failure or ventricular arrhythmias. Immediate reperfusion strategies are crucial in management. Although CABG is considered to be the typical treatment, PCI has shown to have good short-term results.

 

TC- Oct 2016 - 017 - Writers Art pg 18

 

References:

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